Setting the valus of variable present in an Arraylist which is present in another arraylist

i am trying to build an application in which i have a array list inside another arraylist. i am using indexed properties also. i am able to fetch the values of the variables in arraylists but i am not able to save the values back to them.
here is my JSP code:

Here is my form bean:

I am not able to set the value of estimates variable in Deliverable which is a item of deliverableList arraylist.